What Is A Typical/Expected Amount Of Frame Rate Jitter In IP Cameras?

Recently while helping a non-tech proprietor friend configure their newly acquired NVR, I had one of those unexpected moments that seem to come when you are explaining something you know comparatively well to someone who doesn't. And then they ask the question: "How come if the frame rate is set to 10 FPS are there many seconds where there are only 7 and some where they are over 11?" And I gave a smug, assured answer that the configured framerate was actually just a target, and the indicated framerate just a average. And then came the "well whatever, but its way jerky" and "the old one didn't do that". Mind you there is no integrator to blame for failed expectations; the patient self-medicated thru the internet because of confidence gained in mastering the old analog system. So we played with the frame rate a bit but still there was significant "jerkiness" and the occasional quarter second hiccup. We have all seen this to some degree, so maybe were hardened to it, but seeing it thru the eyes of someone naive can make you think again.

So how do you know what's normal jitter and what's indicative of something actually awry? 10%, 20%, if you can see it at all? Does the recorder use a camera-set timestamp of the frame to eliminate jitter on playback? Are there any IP cameras/nvr's known to be super smooth? As good as a consumer's camcorder? Thanks.


"How come if the frame rate is set to 10 FPS are there many seconds where there are only 7 and some where they are over 11?"

How does he know that it went down to 7 or up to 11? Is there an on screen display / read out? Or is he guessing?

And going from 11 to 7 fps is 'way jerky'? This is the type of thing where a short video clip would help understand what is going on.

What camera was this? What NVR?

How does he know that it went down to 7 or up to 11? Is there an on screen display / read out? Or is he guessing?

He couldn't tell, I did, by scrubing the video forward one frame at a time and looking at the timestamp, to millisecond precision.

It looked like a Shenzhen Special, cost was around $800, came with 8 SD bullets. You get what you pay for. I may have given the false impression that he was dissatisfied. He's was not; after I said it was normal, he dropped it. He was too much reveling in his "bargain-hunter-bias" to care anyway. Since its so cheap its probably working within expected tolerances. But what are those tolerances? Have you never seen excessive framerate jitter in person? How did you know it was excessive? What about that bill flipping test 30-60 fps shoot out, what was the jitter there?

I'll get a clip if you insist, but that's not the point. I'm not asking for someone to look at a clip and say thats normal or not, or try this or try that. My friends statements only instigated the actual question, of which the discussion is titled. If its too broad or idiotic, say why and I'll refine or drop it.

"It looked like a Shenzhen Special, cost was around $800, came with 8 SD bullets"

$800 for 8 SD bullets and a NVR? Sounds more like Shernzhen scam to me. That's pretty expensive.

Pretty much any mainstream SD or HD camera can handle 10fps consistently no problem (presuming local connection over a 'regular' network). Maybe he had a crappy, super under powered NVR?